Process of incorporating additives into photographic emulsions

ABSTRACT

The emulsification of additives into a photographic emulsion is stabilized by combining the additive with mono aryl esters or mono cycloalkyl esters of a succinic acid that has a long chained aliphatic substituent.

United States Patent [1 1 [111 3,765,897 Nittel Oct. 16, 1973 PROCESS OFINCORPORATING [58] Field of Search 96/100, 97, 84, 114.5

ADDITIVES INTO PHOTOGRAPHIC EMULSIONS [56] References Cited Inventor:Fritz Nittel, Cologne, Germany Agfa-Gevaert Aktiengesellschaft,Leverkusen, Germany Filed: Oct. 7, 1971 Appl. No.: 187,554

Assignee:

Foreign Application Priority Data Oct. 9, 1970 Germany P 20 49 689.3

US. Cl 96/100, 96/84, 96/97,

96/1145 Int. Cl G03c 1/40 UNITED STATES PATENTS 3,689,271 9/1972 Nittelet al 96/100 Primary Examiner-Norman G. Torchin AssistantExaminer-Richard L. Schilling Attorney-Arthur G. Connolly et al.

10 Claims, No Drawings PROCESS OF INCORPORATING ADDITKVES llNTOPHOTOGRAPHIC EMULSKGNS The present invention relates to a process forincorporating substances in materials which are used to formphotographic layers and auxiliary layers.

It is already known that emulsifiable compounds such as color couplers,UV absorbers, white toners and similar additives may be incorporated ingelatin solutions by using so-called oil forming agents. According toU.S. Pat. Nos. 2,322,027 and 2,533,514, for example, color couplers usedin the production of photographic products are incorporated in emulsionsby dissolving the color coupler in an organic liquid of relatively highboiling point which is insoluble in water, and emulsifying or dispersingthe solution in the emulsions. This process has the disadvantage thathydrophilic developers, e.g., N-butyl-N-w-sulphobutyl-pphenylenediamine,penetrate the oil droplets only to a slight extent, if at all. Thiscauses loss in sensitivity, flattening of the gradation and a reducedimage density. Also residues of hydrophobic developer may be retained inthe droplets and cause fogging when the photographic material is treatedin oxidizing bleaching baths.

l-lydrophilic substances such as color couplers which carry a carboxylgroup are incorporated in gelatin in the form of their sodium salts.Since the gelatine solutions are subsequently adjusted to a pH of 6.2 to6.5, these compounds are generally present in microcrystallinedistribution. The protective colloidal action of gelatin is in manycases insufficient, so that recrystallization occurs influencingsensitivity, gradation and color brilliance in an uncontrollable manner.

Although hydrophilic substances such as color couplers which carry SO Hgroups are generally more compatible with gelatin than the abovementioned compounds, recrystallization still occurs in manycases duringdigestion of the gelatine, especially in the case of compounds that havean enolate form which promotes solubility in an alkaline medium. At thepH values of 6.2 6.5 to which most emulsions are adjusted, the action ofthe S Na group in preventing recrystallization is no longer sufficient.This again leads to a loss in sensitivity, reduction in the colorbrilliance and loss in gradation. The use of lithium salts and increasedamounts of wetting agents has been found to also bring no significantimprovements.

Numerous hydrophilic substances of the above mentioned types, moreover,have the property of increasing the viscosity of the casting solution,-in some cases to such an extent that such solutions can no longer beworked up. i

It is an object of the present invention to provide an incorporationprocess which does not have the above mentioned disadvantages.

In our patent application Ser. No. 814,808, now U.S. Pat. No. 3,689,271,filed Apr. 9, 1969 there have been descirbed compounds of the generalformula wherein R means asaturated or unsaturated alkyl radi cal of atleast five carbon atoms and Q possibly contains the group COX, withXhaving various meanings.

These compounds are said to prevent crystallization and to favor thecoupling of oxidized color developers, especially of hydrophilicoxidized color developers. I now have found new compounds which are evenmore useful in emulsifying additional substances such as color couplers,UV absorbents, white toners or stabilizers in hydrophilic binders forphotographic layers.

The compounds according to the present invention correspond to theformula:

The following compounds have proved to be e555 cially suitable:

din-c 0 oQ-om (mixture 0 and p) DOC-( 3H:

din-o o O E The above long chained aliphatic radicals are generallyisomeric mixtures. In addition to the alkyl radicals represented in theexamples, which in most cases contain one unsaturated bond, hydrogenatedalkyl radicals HO O C-CH-CnHzv Hr-COOQCHO ClsHJs-CH-C O OH Hz-CO O cm-ores o 011 cal-coo- CmHw-CH-GO OH xiasi w v s th San .s

The compounds according to the invention are prepared by reactingsuitable phenols or'cyclohexyl alco- .hols with long chained substitutedsuccinic acid anhydride in a known manner, preferably in the presence ofacid or' basic catalysts, such as sulfuric acid or pyridine. In thisreaction, the succinic acid anyhdride ring is opened with formation ofan ester bond and a carboxyl group. Products in which the long chainedradical is in the d-pOSltlOl'l to the carboxyl group and those in whichit is in the fi-position to the carboxyl group are formed side by side.For the sake of simplicity, only one of these forms is represented inthe general formula and in the examples, but the invention is not thuslimited to hi .99, 9L1-, m r

in cases where the compounds according to the invention contain severalsubstituted succinic acid radicals, these are preferably the sameradicals although in principle the cyclohexyl or aryl alcohols could bereacted with mixtures of variously substituted succinic acid anhydridesto yield compounds which contain vargusspqsivis a i radicals lly} stribvThe process according to the invention is generally carried out asfollows:

Substances which are capable of being emulsified, e.g., color couplers,UV absorbents, white toners, stabilizers or developers, are dissolved inan organic solvent which is immiscible with water, together with thecompounds which are to be used according to the invention and theresulting solution is emulsified in the casting solution for thephotographic layer by means of an if The compounds form soaps inalkaline pH ranges, in

other words, in the course of development. In contrast to lowercarboxylic acids or those which have only a short fatty acid radical,the compounds described here are not washed out in an alkaline medium.They, therefore, prevent precipitation of the dyewhich is formed in thecoupling reaction, and the occurrence of uneven colour surfaces. Thecrystallization of color couplers, which may otherwise already occurduring the process of digestion, is also prevented. Furthermore, incontrast to the known hydrophobic oil-forming agents, the compounds usedaccording to the invention cause neither flattening of the gradation nora reduction in the image.

density. They also largely prevent the increase in viscosity which manycolor couplers containing COOH or SO l-l groups cause in the process ofdigestion.

The compounds according to the invention have the following advantagesover the compounds described in patent application Ser. No. 814,808.

The tendency to crystallization of the substances which are to beemulsified is even more effectively suppressed so that even substanceswhich have a very high tendency to crystallize may be emulsified withoutrecrystallization taking place. When compounds to be emulsified areemulsified in the presence of the compounds according to the invention,only slight clouding of the wet layers is observed. The refractive indexis practically the same as that of dry gelatin so that no opalescenceoccurs. This is paricularly important when UV absorbents, e.g. those ofthe benzotriazole type, are used in the protective layer over colorphotographic materials. If the auxiliary substances according to theinvention arenot used, the opalescence is so severe that the black partsof the image have a bluish appearance.

The compounds described here are generally used in the proportion of 0.1to parts by weight for each part by weight of the substance which is tobe incorporated, the proportion being preferably within the range of 0.3to 1 part by weight. The higher concentrations of up to 10 parts byweight are useful for those cases' in which only small quantities ofadditive, e.g., a stabilizer, should be introduced into the castingsolution. Examples of particularly suitable organic solvents which arenot miscible with water are chlorinated short chained aliphaticcompounds, e.g., methylene chloride, as well as ethyl acetate anddiethyl carbonate.

The binder used for the photographic layers is preferably gelatinalthough this may be partly replaced by other film-forming natural orsynthetic polymers, e.g., alginic acid and its derivatives such as itssalts, esters or amides, earboxymethyl cellulose, alkyl cellulose,starch and its derivatives, polyvinyl alcohol, copolymers containingvinyl alcohol and vinyl acetate units, polyvinyl pyrrolidone and thelike, anionic polyurethanes and other latices, e.g., copolymers ofacrylic acid esters, acrylonitrile or acrylamide.

The photographic layers may contain all the known 5 additives such asanti-fog agents, stabilizers, hardeners, plasticizers and wettingagents. Furthermore, they may be both chemically and spectrallysensitized.

The light-sensitive emulsions may be chemically sensitized by carryingout the ripening process in the pres- 10 ence of small quantities ofcompounds which contain sulfur, for example allyl isothiocyanate, allylthiourea or sodium thiosulfate, or they may be sensitized by means ofthe compounds described in Belgian Pat. specifications Nos. 493,464 and568,687, the iminoaminomethane sulfinic acid compounds described inBelgian Pat. specification No. 547,323, or small quantities of noblemetal compounds such as compounds of gold, platinum, palladium, iridium,ru-

thenium and rhodium. The emulsions may also be sensitized withpolyalkylene oxide derivatives, elg., polyethylene oxide having amolecular weight of between 1,000 and 20,000, condensation products ofalkylene oxides and aliphatic alcohols, glycols, cyclic dehydrationproducts of hexitols, alkyl-substituted phenols, aliphatic carboxylicacids, aliphatic amines, aliphatic diamines and amides. The condensationproducts have a molecular weight of at least 700, and preferably morethan 1,000. These sensitizers may, of course, be combined in order toobtain special effects, as described in Belgian Pat. specification No.537,278 and in British Pat. specification No. 727,982.

EXAMPLE 1 NHCOCHzO-QCtHn sHn and 20 g of Compound 7 dissolved in 160 ccof ethyl acetate are emulsified in 1 kg of a 10 percent gelatinesolution at C. 'After removal of the solvent in a thin layer evaporator,the emulsion is added to 1 kg of a red sensitized silver halide gelatineemulsion which contains 0.33 mol of silver bromide, 0.0075 of silveriodide 50 and g of gelatine per kg.

The resulting mixture is used within a colour photographic multilayeredmaterial in the usual manner as a red-sensitive layer which contains.cyan-forming coupier.

Flattening of the gradation and reduction in the image density which arecaused by the known hydrophilic developers do not occur in this case.

EXAMPLE 2 40g ofthe following cyan-forming coupler:

and g of Compound 12 are together emulsified in l kg of a 10 percentgelatin solution as described in Ex ample l. The emulsion is added to 1kg of a red sensitised silver halide gelatine emulsion described inExample l. 5

The same results are obtained after the mixture has been worked up asdescribed in Example 1.

EXAMPLE 3 g of the following magenta-forming coupler:

in 1 kg of a 10 percent gelatin solution as described in Example 1 andadded to 1 kg of a green sensitised silver halide gelatin emulsion.

The mixture is worked up as in Example l. The green-sensitive layer withregard to gradation and density shows the properties described. inExample 1.

EXAMPLE 4 3 8 of fel wesllw figi s N rHu and 10 g of Compound 25 aredissolved in ethyl acetate and emulsified in 1 kg of a 10 percentgelatin solution. The emulsion is cast as a UV protective layer over acolor photographic material.

The protective layer prepared by the process accord- ,ing to theinvention is clear, whereas a layer which has awareness! .wiflzww npqsss2229315 9951 1;-

EXAMPLE 5 30 g of the UV absorbent used for Example 4 and 15 g ofCompound 8 are dissolved in ethyl acetate and emulsified in 1 kg of a 10percent gelatin solution. The emulsion is cast as a UV protective layerover a color photographic material. The result is similar to thatobtained in Example 4.

EXAMPLE 6 g of the following white tonerz W on. I as N \N 0 C tisHtr-CHC O OH and 2.5 g of Compound 20 are dissolved in 10 ml ofethanol and 10 ml of methyl chloride and emulsified in 1 kg of a 10percent gelatin solution. The emulsion is cast as the uppermostprotective layer over a color photographic material in which one of thelower protective layers is a UV protective layer. The fluorescence ofthe white toner is in no way impaired and no crystallization occurs.

EXAMPLE 7 The UV absorbent of Example 4 is dissolved in ethyl acetateand portions of this solution separately mixed the following oilformers:

I c rH1 -CHC 0 0H CH:C0O-C9Hl0(i50) (from Serial No. 814,808)

CuHrCH-C O OH CH1C 0 O-GgHn (from Serial No. 814,808)

A... COO@ (compound 31 of this application) (compound 27 0! thisapplication) Each solution is poured on a glass plate and the solvent iis evaporated. The Table indicates when crystallization of the UVabsorbent occurs.

TABLE oil-former added crystallization to 1 part of UV absorbentobserved after no addition 5 minutes [.5 parts of! 45 minutes 2 parts ofl 2 hours 1.5 parts of l] 1 hour 2 ports of ii 2 hours 1.5 parts of ll!no crystallization after 24 hours 2 parts of Ill no crystallizationafter 24 hours 1.5 parts of N no crystallization after 24 hours 2 partsof IV no crystallization after 24 hours I claim:

1. in the process of emulsifying materials into an aqueous dispersion ofa hydrophilic photographic binder with an oil former that stabilizes theemulsion, the improvement according to which the oil former has lesmuiaa RCHCOOH R- H-COwO-R' wherein one R is hydrogen and the other isa saturated or unsaturated straight chained or branched aliphaticradical having six to 18 carbon atoms, and R a cycloalkyl group, an arylgroup or a heterocyclic aromatic group. bg m i ati of la m. tiwhqhtbshin i solved in a volatile water-immisicible short chain aliphaticsolvent along with the oil former, and the solution thus formed isemulsified into the gelatin emulsion.

3. The combination of claim 2 in which the organic solvent is methylenechloride.

4. The combination of claim 2 in which the organic solvent is diethylcarbonate.

5. The combination of claim 1 in which the binder is gelatin, thematerial to be emulsified is soluble in aqueous alkali, and is dissolvedin an aqueous alkaline solution along with the oil former and theresulting solution emulsified into the gelatin emulsion.

6. In a photographic gelatin emulsion containing emulsified photographicadditive particles and an oil former that stabilizes the emulsion, theimprovement according to which the oil former has the formula:

wherein one R is hydrogen and the other a saturated or unsaturatedstraight chained or branched aliphatic radical having six to 18 carbonatoms, and .w R a cycloalkyl group, an aryl group or a heterocyclicaromatic group. 7. The combination of claim 6 in which R is substit ledwith another radical of the formula:

R-CH-COOH 9. The combination of claim 6 in which the photographicadditive is a UV absorber.

10. The combination of claim 6 in which the photoa white toner.

IIK i l graphic additive is

2. The combination of claim 1 in which the binder is gelatin and thematerial to be emulsified is first dissolved in a volatilewater-immisicible short chain aliphatic solvent along with the oilformer, and the solution thus formed is emulsified into the gelatinemulsion.
 3. The combination of claim 2 in which the organic solvent ismethylene chloride.
 4. The combination of claim 2 in which the organicsolvent is diethyl carbonate.
 5. The combination of claim 1 in which thebinder is gelatin, the material to be emulsified is soluble in aqueousalkali, and is dissolved in an aqueous alkaline solution along with theoil former and the resulting solution emulsified into the gelatinemulsion.
 6. In a photographic gelatin emulsion containing emulsifiedphotographic additive particles and an oil former that stabilizes theemulsion, the improvement according to which the oil former has theformula:
 7. The combination of claim 6 in which R'' is substituted withanother radical of the formula:
 8. The combination of claim 6 in whichthe photographic additive is a color coupler.
 9. The combination ofclaim 6 in which the photographic additive is a UV absorber.
 10. Thecombination of claim 6 in which the photographic additive is a whitetoner.